The invention relates to an apparatus for axially adjusting a shifting element, it being possible for the shifting element to be, for example, the slider sleeve of a manual transmission for vehicles or the cam carrier of a valve train for an internal combustion engine.
DE 10 2005 003 079 A1 discloses a valve train for an internal combustion engine, having a camshaft, on which a cam carrier and two worm drives for axially adjusting the cam carrier are provided. Each worm drive is assigned an actuator with an actuating pin, the actuating pin being arranged such that it can be displaced radially in relation to the camshaft. It is possible for said actuating pin to be brought selectively into engagement or out of engagement with the associated worm drive. Here, the one worm drive with its associated actuator brings about an axial movement of the cam carrier from a first shifting position into a second shifting position, whereas the other worm drive with its associated actuator makes an opposite axial movement back into the first shifting position possible.
It is an object of the invention to provide a particularly compact apparatus for axially adjusting a shifting element, which apparatus ensures a desired axial adjustment by way of low structural complexity.
This and other objects are achieved according to the invention by way of an apparatus for axially adjusting a shifting element, having a shift shaft which can be rotated about an axis, an actuating body which is connected to the shift shaft fixedly so as to rotate with it and in an axially displaceable manner, and, on a circumferential face, has at least two slotted guide sections which are configured as a groove, and a linear actuator which is assigned to the actuating body and has an actuable actuator pin which can engage into the slotted guide sections for axially displacing the actuating body. Each slotted guide section has an engaging region for the actuator pin, an opposite disengaging region for the actuator pin, and an actuating region which lies in between in the circumferential direction and is bent in a curved manner for axially displacing the actuating body. The disengaging region and the engaging region of slotted guide sections which are adjacent in the circumferential direction are arranged at the same axial position. In this way, the shifting element can be adjusted axially in opposite directions by way of only a single linear actuator. The result is that a desired shifting position of the shifting element can be realized with low complexity.
In accordance with one embodiment, slotted guide sections which are adjacent in the circumferential direction merge into one another and form a slotted guide which runs continuously in the circumferential direction. In other words, this means that the slotted guide which is configured as a groove and runs in the circumferential direction does not have any discontinuity points, that is to say it does not have any “gaps” in the axial direction.
As an alternative, slotted guide sections which are adjacent in the circumferential direction can be spaced apart from one another, with the result that there are groove-free sections in the circumferential direction between said slotted guide sections which are configured as a groove. The groove-free sections make relatively simple engaging and disengaging of the actuator pin into the slotted guide sections possible.
The engaging regions and/or the disengaging regions of the slotted guide sections are preferably configured at least in sections as ramps for reducing a radial groove depth. The ramps likewise contribute to relatively simple engaging and disengaging of the actuator pin into the slotted guide sections which are configured as a groove. Furthermore, in the case of a suitable sensor system in the linear actuator, the passage through an engaging region and/or a disengaging region can also be determined via the radial position of the actuator pin, which radial position is changed by way of the ramps.
The engaging region and the opposite disengaging region of an (in particular, every) slotted guide section are particularly preferably spaced apart axially from one another. As a result, the actuating body is displaced axially in a desired way by way of the axially fixed linear actuator between the engagement and the disengagement into the slotted guide sections which are configured as a groove.
In accordance with one embodiment of the apparatus for axially adjusting a shifting element, the actuating body has precisely two slotted guide sections which preferably extend over in each case approximately 180°.
As an alternative, the actuating body can have precisely four slotted guide sections, each of the slotted guide sections preferably extending over approximately 90° in this case.
In general, the actuating body can have an even number of slotted guide sections, each slotted guide section preferably extending over approximately 360°/number of slotted guide sections in this case.
Otherwise, a rotational angle sensor for determining the rotational position of the actuating body is preferably provided. The detection of the rotational position of the actuating body is advantageous, in particular, when the actuating body has more than two slotted guide sections, and at least two engaging and disengaging regions of the actuating body are arranged at the same axial position.
In the case of the apparatus for axially adjusting a shifting element, the shift shaft can be, for example, a camshaft and the shifting element can be a cam carrier.
In accordance with one preferred, alternative embodiment of the apparatus, the shifting element is a slider sleeve of a manual transmission for vehicles.
Accordingly, the invention also includes a manual transmission for vehicles, having a drive shaft and the above-described apparatus for adjusting a shifting element, the drive shaft being connected in gear terms to the shift shaft or being identical to it.
In accordance with one design variant of the manual transmission, the drive shaft and the shift shaft are coupled by way of a gear mechanism with a fixed transmission ratio. Here, the rotation of the drive shaft is preferably stepped down by way of the transmission. Therefore, relatively long response and shifting times of the linear actuator can also be accepted, and the costs for the linear actuator can therefore be reduced.
Here, the actuating body and the shifting element can be coupled in the axial direction by use of a spring element. The axial elastic coupling provides an overload safeguard and prevents the manual transmission from being damaged by way of an axial adjusting movement of the actuating body in the case of an axially blocked shifting element.
In accordance with an alternative design variant of the manual transmission, the gear mechanism drive shaft corresponds to the shift shaft, and the actuating body is identical to the shifting element. As a consequence, the slider sleeve corresponds to the shifting element and, moreover, also has the slotted guide sections. The number of individual components can advantageously be reduced as a result. However, a relatively great amount of axial installation space is required in the region of the slider sleeve, in order to form the slotted guide sections and to arrange the linear actuator in an adjacent manner with respect thereto.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.